The present invention relates to a gas distribution arrangement for the admission of a processing gas to an atomizing zone around an atomizing device coaxially arranged in an atomizing chamber, the processing gas being admitted from a horizontal, helical inlet duct through an annular orificial slit, which is in rotational symmetry with the axis of the chamber, into a space between two coaxial guide walls around and above the atomizing device, said orificial slit being provided with guide vanes to impart to the flow of processing gas a change of direction from a substantially exclusively tangential flow in the helical duct to a predominantly radial flow into the space between the coaxial guide walls.
A gas distribution arrangement of this nature is known from the specification pertaining to U.S. Pat. No. 4,227,896 to Larsson et al., corresponding to Danish Pat. No. 141,671, and as in the case of the invention dealt with therein the term atomizing chamber should also in connection with the present invention be understood as a treatment chamber for various processes, such as drying, cooling, and absorption, wherein a liquid, which may be a pure substance, a solution or a suspension, is atomized by means of an atomizing device, such as a rotating atomizing wheel, which is coaxially disposed in the normally substantially cylindrical atomizing chamber.
Furthermore, from the specification pertaining to U.S. Pat. No. 4,226,603 to Larsson et al., corresponding to Danish Pat. No. 141,793 another gas distribution arrangement of the nature referred to in the introduction is known, comprising two separate sets of guide vanes disposed in the orificial slit one above the other.
The objects of the former of these known gas distribution arrangements are to obtain at the internal aperture of the orificial slit facing the conical guide duct an optimal and in respect to rotational symmetry uniform distribution of the processing gas admitted in the helical duct, and with a substantially reduced pressure drop over the orificial slit, and furthermore already at this place a definite piloting of the flow of gas into a downward spiral path with a comparatively low rotation component in the conical guide duct, and these objects are obtained by having the guide vanes comprise two radially succeeding sets of fixed, plate-shaped guide vanes, of which the radially outer set of vanes deflects the flow of gas into having a predominantly radial velocity component, whereas each vane in the inner set of vanes protrudes into the space between the innermost parts of adjacent vanes in the outer set of vanes and extends substantially parallel with the innermost tangential planes of same.
However, by this arrangement it cannot be avoided that in the course of the flow of gas from the outer set of plate-shaped guide vanes into the spaces between the inner set of plate-shaped guide vanes, eddies involving losses and also sudden changes of velocity will occur owing to abrupt changes of direction and of cross sections of the flow, resulting in a pressure drop and an increased power consumption for supplying the processing gas.